1. Field of the Invention
The present invention relates to a controller of a starter that cranks an engine of a vehicle to start the engine.
2. Description of Related Art
A technology for controlling energization to a motor of a starter (starter motor) that cranks an engine is described in Patent document 1 (JP-A-2004-308645), for example. In Patent document 1, a parallel circuit of a resistor (starting resistor) for suppressing inrush current and a short-circuit relay for bypassing the resistor by short-circuiting its contacts (i.e., by switching on) is provided in an energization route from a battery as a power supply to the starter motor. When the energization to the starter motor is started, following control is performed. That is, current suppressed by the resistor is passed to the starter motor by opening the contacts of the short-circuit relay. Thereafter, the resistor is made ineffective by closing the contacts of the short-circuit relay to apply the entire voltage of the battery to the starter motor. With such the control, the inrush current during the start of the energization to the starter motor is suppressed and fall of the battery voltage (power supply voltage) is suppressed.
Patent document 2 (JP-A-H11-30139) describes a starter constructed to be switchable between a state where a pinion gear rotated by a motor is engaged with a ring gear of an engine and a state where the pinion gear is disengaged from the ring gear independently from energization to the motor.
If a fixation abnormality occurs in the short-circuit relay and a state where the contacts of the short-circuit relay remain closed is caused in the technology of Patent document 1, the resistor cannot be effected during the start of the engine, so the fall of the battery voltage cannot be suppressed.
If the battery voltage falls largely in each engine start, charge of the battery is necessitated after the completion of the engine start. As a result, charge and discharge of the battery is performed frequently.
Such the frequent charge and discharge of the battery leads to exhaustion of the battery (performance degradation). If an alternator is rotated to charge the battery, torque to be generated by the engine increases, and eventually a fuel consumption deteriorates.
If a state where the short-circuit relay remains open is caused, the resistor remains in the energization route to the starter motor. An electricity consumption and heat generation in the resistor during the energization to the starter motor (during engine start) increase significantly. If the resistor is cut by the heat generation, the energization to the starter motor cannot be performed and the engine cannot be started thereafter.
Therefore, it is desirable to detect occurrence of an uncontrollable abnormality in a section for suppressing the inrush current to the starter motor such as the above-mentioned resistor or the short-circuit relay and to perform some treatment.